add groups section in the getting started guide.
Suggest to prefer configuration with env vars instead of modifying
the default configuration file
Signed-off-by: Nicola Murino <nicola.murino@gmail.com>
If you prefer to auto-create the first admin you can enable the
"create_default_admin" configuration key and SFTPGo will work as before.
You can also create the first admin by loading initial data: now you can
set both username and password, before you could only change the password
X-Forwarded-For, X-Real-IP and X-Forwarded-Proto headers will be ignored
for hosts not included in this list.
This is a backward incompatible change, before the proxy headers were
always used
